"""
【自定义分页组件】
以后如果想要复用这个分页组件，需要做的事情如下：
（1）在视图函数中
def pretty_list(request):
    #1、根据需求筛选数据
    queryset = models.PrettyNum.objects.all()
    #2、实例化分页对象
    page_object = Pagination(request,queryset)
    #参数字典
    context = {
        "queryset": page_object.page_queryset,  #分完页的数据
        "page_string": page_object.html(),      #生成的页码
    }
    #返回值
    return render(request, "pretty_list.html", context)
（2）在html页面中
            处理数据
            {% for qurey in qureyset %}
                obj.xxx
            {% endfor %}
            分页样式
            <ul class="pagination">
                {{ page_string }}
            </ul>
"""
from django.utils.safestring import mark_safe
class Pagination(object):
    def __init__(self,request,queryset,page_size=10,page_param="page",plus = 5):
        """

        :param request: 请求的对象
        :param queryset:符合条件的数据（根据这个数据给他进行分页处理）
        :param page_size:每页显示多少条数据
        :param page_param:在URL中传递的获取分页的参数，例如：/pretty/list/?page=1
        :param plus:显示当前页的前或后几页（页码）
        """
        #获取URL
        from django.http.request import QueryDict
        import copy
        query_dict = copy.deepcopy(request.GET)
        query_dict._mutable = True
        self.query_dict = query_dict
        self.page_param = page_param
        #获取当前页
        page = request.GET.get(page_param,"1")
        #判断是否是十进制数
        if page.isdecimal():
            page=int(page)
        else:
            page=1

        self.page = page
        self.page_size = page_size

        self.start = (page - 1) * page_size
        self.end = page * page_size

        self.page_queryset = queryset[self.start:self.end]

        # 获取数据库中的数据条数
        total_count = queryset.count()
        # 总页数
        total_page_count, div = divmod(total_count, page_size)  # divmod除法函数，返回值：商，余数
        if div:
            total_page_count += 1
        self.total_page_count = total_page_count
        self.plus = plus

    def html(self):
        # 设置按钮显示范围
        if self.total_page_count <= 2 * self.plus + 1:
            start_page = 1
            end_page = self.total_page_count + 1
        else:
            # 当前页小于5
            if self.page <= self.plus:
                start_page = 1
                end_page = 2 * self.plus + 1
            else:
                if (self.page + self.plus) > self.total_page_count:
                    start_page = self.total_page_count - 2 * self.plus
                    end_page = self.total_page_count
                else:
                    start_page = self.page - self.plus
                    end_page = self.page + self.plus + 1

        # 页码列表
        page_str_list = []
        #获取url全部参数
        self.query_dict.setlist(self.page_param,[1])
        # 首页
        page_str_list.append('<li><a href="?{}">首页</a></li>'.format(self.query_dict.urlencode()))
        # 上一页
        if self.page > 1:
            self.query_dict.setlist(self.page_param, [self.page - 1])
            prev = '<li><a href="?{}">上一页</a></li>'.format(self.query_dict.urlencode())
        else:
            self.query_dict.setlist(self.page_param, [1])
            prev = '<li><a href="?{}">上一页</a></li>'.format(self.query_dict.urlencode())
        page_str_list.append(prev)
        # 页码
        for i in range(start_page, end_page):  # range前取后不取，所以还要加一
            self.query_dict.setlist(self.page_param, [i])
            if i == self.page:  # 当前页显示按钮样式
                ele = '<li class="active"><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            else:
                ele = '<li><a href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            page_str_list.append(ele)
        # 下一页
        if self.page < self.total_page_count:
            self.query_dict.setlist(self.page_param, [self.page + 1])
            prev = '<li><a href="?{}">下一页</a></li>'.format(self.query_dict.urlencode())
        else:
            self.query_dict.setlist(self.page_param, [self.total_page_count])
            prev = '<li><a href="?{}">下一页</a></li>'.format(self.query_dict.urlencode())
        page_str_list.append(prev)
        # 尾页
        self.query_dict.setlist(self.page_param, [self.total_page_count])
        page_str_list.append('<li><a href="?{}">尾页</a></li>'.format(self.query_dict.urlencode()))
        # 输入框
        search_string = """
                <li>
                            <!--输入框组件-->
                            <form style="float: left;margin-left: -1px" method="get">
                                    <input name="page"
                                           style="position: relative;float: left;display: inline-block;width: 80px;border-radius: 0;"
                                           type="text" class="form-control" placeholder="页码">
                                    <button style="border-radius: 0" class="btn btn-default" type="submit">跳转</button>
                            </form>
                        </li>
            """
        page_str_list.append(search_string)
        page_string = mark_safe("".join(page_str_list))
        return page_string